Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int n, m;
char c[55][55];
int dis[55][55];
const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};
int main() {
	scanf("%d%d", &n, &m);
	for (int i = 0; i < n; ++ i) scanf("%s", c[i]);
	memset(dis, -1, sizeof dis);
	queue <pair <int, int> > q;
	dis[0][0] = 0;
	q.push(make_pair(0, 0));
	while (!q.empty()) {
		pair <int, int> p = q.front(); q.pop();
		int x = p.first, y = p.second;
		for (int i = 0; i < 4; ++ i) {
			int nx = x + dx[i], ny = y + dy[i];
			if (nx < 0 || ny < 0 || nx >= n || ny >= m) continue;
			if (c[nx][ny] == '#') continue;
			if (~dis[nx][ny]) continue;
			dis[nx][ny] = dis[x][y] + 1;
			q.push(make_pair(nx, ny));
		}
	}
	if (!~dis[n - 1][m - 1]) {
		puts("-1");
		return 0;
	}
	int cnt = 0;
	for (int i = 0; i < n; ++ i) {
		for (int j = 0; j < m; ++ j) {
			cnt += c[i][j] == '.';
		}
	}
	printf("%d\n", cnt - dis[n - 1][m - 1] - 1);
	return 0;
}